Getting my Bio Degree Ruined Mass Effect [spoilers]

So I'm about to graduate with my bachelor's in biology from UCSD, and I'm trying to get a list of video games together that I'm going to binge before Med school, and I've always been fond of the Mass Effect line, but I stopped playing at 2, still kinda followed the story, and now that Andromeda is out, I was thinking about getting back in.I started remembering the story line, all of the alien races, their features and such.... then I wondered, "Are all of these aliens DNA based?" I mean, I figured there would be another type of nucleic acid form of life that would differ at least SLIGHTLY. Unless the trasnspermia theory is 100% proven in that universe, or DNA is the only basis for life in that universe... is that mentioned at all? Too deep? It's like I can't take the whole game seriously anymore lmao